Flow-through devices for removing compounds or other components from a biological fluid are known. For example, flow-through removal devices have been used in medical processing sets where the biological fluid is filtered to remove undesired blood components, such as leukocytes. Flow-through devices have also been proposed for use where the biological fluid has been treated with a solvent or chemical agent as, for example in a pathogen inactivation process.
In many pathogen inactivation processes, a chemical agent is typically added to the biological fluid to either (1) directly inactivate present pathogens or (2) inactivate present pathogens in combination with other means, such as light. Regardless of the method used, after treatment, it is desirable to remove unreacted chemical agents or by-products of the inactivation process from the biological fluid prior to its transfusion to the patient.
One example of such a pathogen inactivation processing system is described in U.S. patent application Ser. No. 09/325,599, which is incorporated herein by reference in its entirety. In the system described therein, fluid from a source container that has been treated in a pathogen inactivation process (e.g., photoactivation with ultraviolet light and a psoralen compound) is passed through a removal device and collected in a receiving container. The removal device includes a sorbent selected to remove residual chemical agent and/or by-products of the inactivation process.
Flow-through devices may also be used in the filtration of blood products to remove, for example, leukocytes from a collected blood product. An example of a fluid processing system that includes a leukoreduction filter in a flow-through arrangement is described in U.S. Pat. No. 6,358,420. Flow-through devices may also be used to remove treating agents used in the treatment of blood or a blood fraction, which agent is desirably removed from the fluid prior to further use of the fluid.
In the above-described examples, the removal device includes a housing and a removal media inside the housing. Regardless of the removal for which the device is used (i.e., leukoreduction, or removal of inactivation compounds or other agents), complete and uniform exposure of the fluid to the removal medium is important. To obtain the greatest efficiency for the removal medium, it is desirous for the fluid to come in contact with as much of the removal medium as possible. For example, to ensure substantially complete removal of the inactivating agent in the pathogen inactivation example described above, it is desirable that the fluid contact the removal media as completely as possible, without bypassing any part of the removal media. Likewise in a leukoreduction device, complete exposure is important to ensure substantially complete removal of leukocytes, which if otherwise transfused, may cause an adverse reaction in the recipient.
To further ensure substantially complete and uniform exposure of the fluid to the media, it is important that the removal media be maintained in a substantially fixed orientation. For example, in a processing set that includes a hanging-type filter where the flow is “top to bottom,” very often, a natural twisting moment causes the filter to hang at an angle. As the weight below the filter changes (i.e., as the collection container fills), the moment increases and the angle changes. A device that tilts away from the central vertical axis may result in uneven distribution of the fluid across the removal media, resulting in incomplete exposure and removal of the undesired agents.
In addition to uniform and complete exposure of the fluid to the media, it is also important, to have substantial processing time consistency (i.e., reproducibility) from one device to the next.
It is also desirable that a device that meets the above performance requirements is also easy and economical to manufacture with a low rejection rate.
The above objectives are addressed by the present invention.